The tissue removal for one diopter of refractive error is approximately 12 microns, based upon the Munnerlyn formula. The physics of this calculation are the same across different excimer laser platforms.

Wavefront-enhanced ablations attempt to correct refractive error based upon a more detailed analysis of the error. Commonly, wavefront-enhanced ablations require more tissue per diopter of correction. Each laser manufacturer uses a propriatary formula for wavefront-guided correction, so each can be different. Additionally, the tissue removal is not uniform, so there will be some areas with more removal and some with less.

Current laser systems have the ability to determine in advance, and with reasonable accuracy, how much tissue will be removed and where. This can be compared to the patient's cornea's thickness to affirm safety.